Control device for electric circuits



March 28, 1933. F. R. WEST El AL CONTROL DEVICE FOR ELECTRIC CIRCUITS 3 Sheets-Sheet 2 Filed Dec.

W a Z z PM 4 9L 4 u W 4/ H a All s 3 4 4 w m f w 9 4 i \M DHPHM m m M Y W m ATTORNEY.

March 28 1933. Rf WE ET AL 1,902,926

CONTROL DEVICE FOR ELECTRIC CIRCUITS Filed Dec. 24', 1927 3Sheets Sheet s INVENTORS.

, ,5 M a/pvvu ATT RNEY.

Patented Mar. 28, 1933 UNITED STATES PATENT ()FFICEF FRANK R. WEST AND THOMAS E. CAR ENTER, or DETROIT, MICHIGAN; SAID C RPENTER ASSIGNOR. To SAID WEST a CONTROL DEVICE FOR ELECTRIC CIRQUITs Application filed December 24, 1927. Serial No. 242,490.

This invention relates to a control'device for electric circuits. It has to do particularly with a novel, compact and positively acting thermostat or pressure control device, especially adapted for refrigerating systems and utilizing mercury as the making and breaking medium.

Heretofore in the manufacture of makeand-break control devices utilizing mercury bulb switches it has been found desirable to give the control lever a relatively quick snap action in an attempt to give a quick make and break between the flow of the mercury and the contact points inside the mercury bulb. This accelerating of the making and brealc ing action has been found necessary in order to reduce the arcing of the electric current which tends to oxidize the mercury and at the same time create heat and cause eXpansion and accumulation of pressure inside the mercury bulb which soon tends to fracture the bulb. While such control devices of the past have greatly increased the snap action incident with the making and breaking of the electric circuit, such snap action has not been quick enough to entirely eliminate the arcing between the electrodes or contact points and the mercury, and in spite of the increasing of the snap action and the decreasing of the arcing in the bulb, mercury bulbs have heretofore lasted only a relatively short time.

It is the object of the present invention to so operate the mercury bulb, forming a part of the mercury bulb switch, as to give it a greatly accelerated and positive snap action at the time of making or breaking the contact, and only at such time, whereby to completely eliminate all destructive arcing with in the mercury bulb. More specifically, this invention contemplates the method of covering or uncovering the contacts of the mercury tube by first delaying the moving of the body J of mercury ust prior to the making or break ing, and then giving the body of mercury a very quick snap action so as to positively cover or uncover the contacts and prevent the mercury from running apart slowly, or mercury globules formingand runningtogether slowly and arcing or completing the circuit before being snapped. into position. This novel manner of positively making or break-' ing the circuit is accomplished by a very simple and compact control device which includes a mercury switch of standard type actuated by spring pressed toggle mechanism which is connectedto the switch structure by means of a suitable pin-and-slot connection which permits the toggle mechanism to be moved to dead center previous to snappingwithout imparting as much movement to the mercury bulb as has heretofore been customary. As a result of this connection the mercury bulb-movement is delayed just prior to making or breaking, then as the toggle mechanism passes dead center the mercury bulb is instantly moved or thrown a rela tively great distance to positively move the mercury quickly and as an integral body Other novelmechanism embodied in this control device includes the'pivotall'y but frictionally mounting of the mercury bulb for automatically holding the mercury bulb in any position into which it is thrown the" snapping of the toggle mechanism. Still another feature entering into our novel conibination resides in a novel connection between the power element and the toggle mechanism whereby the mercury bulb is initially moved less than the power element andv the toggle mechanismis allowed to snap without such snapping action being transmitted to the bellows of the power'element, or in other words, the quick snap action of the toggle and mercury bulb is not retarded by inertia and weight of the power element parts.

In the drawings: V Fig. 1 is a front elevation, partially in section of a control device embodying the features of our invention.

Fig. 2 is a side elevation of the structure hown in Fig. 1, theenclosing box being shown in cross section and one'toggle lever being removed.

Figs. 3 to 6 are enlarged fragmentary drawings illustrating the movement of the controlling parts of the device from the normal position of the bulb until the contact points. are covered; Figs. 3, 4', and 5illustrating the limited movement of the bulb just prior tem, but it will be understood that such con 7 trol may be equally well adapted for the making and breaking of an electrical circult 1n other systems and for other structures where a quick, positive snap action is desired.

In the drawings we have illustrated our invention as embodied in a control unit for an electrical operating circuit in a refrigerating system, and in Fig. 1 the power element actuating the control is generally designated 1, and as shown, comprises a suitable chamber enclosing a bellows member 2 which is relatively large as compared to standard practice. This bellows member is suitably connected to a suitable container member 3 which in turn supports and directly actuates a plunger 4 surrounded by a suitable spring 5. The bellows and the member 3 are actuated by means of a suitable fluid introduced through the conduit 6 forming a part of a thermostat or pressure control. A suitable adjusting nut 7 may control the tension on the spring 5 and thus control the time and period of lift of the plunger member 4. It

- i will be understood that the bellows and many parts of the power element may be of any design desired, but that we prefer to use a relatively large diameter bellows member whereby to increase the efifective area and increase the power elements sensitivity to pressure change.

The top of the plunger 4 preferably terminates in a circular head or stud 8. This head 8 may be screwed into, or otherwise 7 i fitted in, the top of the plunger 4 whereby 'to provide a sliding grooved connection be tween theplunger and a shoe 9. This shoe 9 is preferably U-shaped in cross section, as shown in Fig. 2, and is provided with a suitable aperture in its face of approximately the same diameter as the smaller shank of the head 8 whereby the shoe 9 will be freely moved a distance, limited by the head 8 and the top of the plunger 4. The purpose of this connection is to remove the weight and inertia of the power element, as will be more fully described.

A journal pin 10 is adapted to be passed throughsuitable apertures in the upper part of the shoe 9, the ends of the journal extending a short distance beyond each side of the U-shaped sides of the shoe. The portion 11 of thejournal member is adapted to receive the ends of suitable toggle members 12,.

and 13. Each toggle member is provided with a suitable stud 14, one end of which is shaped to pivotally fit around the journal, and the other end of which is of a diameter to receive a suitable coiled'spring, as clearly shown in Fig. 1. Each stud 14 is also provided with a suitable aperture for slidably receiving a pin 15 forming a part of a similar stud 16, which also has an enlarged end forfitting in the coil spring and tapered ball-pointed ends 17 universally mounted in the ends of adjusting screws 18. The studs 16 each con-- sists of an enlarged part fitting in the coil spring and the pins 15, and the studs 14 each consists of an enlarged'part for receiving the other end of the coil springs and are also apertured for receiving the pins 15 of the other studs 16. This structure permits an easy assembly, as it will be'obvious that the studs 14 pivotally fit around the journal 10, and the round ends 17 are held in the sockets of the screws 13 by pressure of the springs. It will thus be obvious that either or both of the toggle members 12 or 13 may be readily removed by merely compressing the coil spring or springs. I

The normal position of the shoe 9 of the toggles 12 and 13 is that shown in Fig. 1, which is the lowermost position past dead center. A bracket 19 connected to the box has a bifurcated extension arm 20 w ich acts as a limit stop so as to prevent the adjusting screw 7 from being disengaged from threads.

A suitable mercury bulb switch unit, which may be generally designated 21 is pivotally supported above the toggle mechanism and shoe by means of a suitable journal 22, as best shown in Fig. 2. The mercury bulb of this switch arrangement is of standard form and may be designated 23, and is supported by means of suitable clips 24 in a frame 25, which is pivotally supported by the journal member 22. The movement of this frame 25 and the mercury bulb 23 is frictionally retarded by means of a coil spring 26 which is mounted on the end of the journal member '22. The connection between the frame 25 of the mercury b-ulband the shoe 9 is by means of a link or turn-buckle 27. The turn-buckle 27 is provided with the usual right and left hand threads whereby the mercury bulb may be readily adjusted relative to the shoe 9. I

It will be obvious that by reason of the pin and slot connection between the shoe 9 and thevframe 25, that whenever the toggles 12 and 13 reach and move past dead center that the bulb 23 will be thrown either up or down ahead of the shoe 9, a distance 01' the length of the slot. This forcible snapping action or, propelling of the bulb gives the mercury therein a positive instantaneous movement which would be impossible to obtain if the connection between the bulb and the toggles were rigid. Further .iore,,the lost motion In the operation of our control device,

assuming, for instance, that the refrigerator is at the correct low temperature, the power element shown in Fig. 1, will be at its lowermost position, the shoe 9 will rest on top of the plunger 4 and the mercury bulb will be in the position shown with the pin 10 atthe bottom of its slot. As the temperature of the refrigerator rises, the pressure or-expansion ofthe fiuid in the conduit 6 will increase to expand the bellows 2, and-as a result, the plunger 4 will slowly rise. In Fig. 3 the mercury'bulb isshown at its lowermost starting position, (which may be adjusted) the pin is at the bottom of its slot and the plunger 4 is gradually being raised coincidentally with the shoe 9. In Fig. 4 the plunger 4 is shown in contacting position with the shoe 9, and just starting to move the toggles 12 and 13 upwardly. In Fig. 5 the plunger has moved the toggles 12 and 13 to their dead center position, the bulb 23 is now ready to be snapped by the pin 10 which is now in contact with the upper end of its slot, and the mercury bulb is now at apoint just preparatory to covering both terminals but being so delayed as not to tend to make the mercury separate or run. As the plungerrises, due to the expansion of the bellows, it will force the shoe 9 and the toggles past dead center, and at the instant the toggles move past dead center, as shown in Fig. 6, the coil springs will force the toggle levers upwardly whereby the pin or ournal 10 is snapped upwardly with a very sharp jerk. This snapping action throws the'bulb 2 3 upwardly the distanceof theslot in which the pin 10 is ,positioned, and the bulb is held'in this snapped position by the friction of the spring 26. The shoe 9 will also be snapped free of the plunger 4, but much slower than the link 27 i and the bulb 2-3. The movement of the bulb body of mercury is instantaneously moved from the position shown in Fig. 5 to the circuit making pos1t1on shown 1n 'Flg. 6, thus positively preventing any separation or running of globules of mercury which. would otherwise permit destructive arcing. i

The movement of the mercury bulb from.

making position to breaking position is somewhat similar to the operation just described and is illustrated in Figs. 7 to 9. Fig. 7 is simi ar toFig. 6 except that the plunger 4 has started downwardly whereby the head 8 of the plunger contacts with the shoe 9. In Fig. 8 the plunger 4 is shown as moved still farther downwardly,-the pin 10 being at the'bottom of the slot, the bulb 23 being slightly moved to a point more nearly horizontal, and the toggles 12 and 13 being moved to approximately dead center position. In Fig. 9 the toggle has been moved past dead'center whereby the mercury bulb and link 27 have been snapped downwardly, and the shoe 9 has been moved to the position shown, whereby the snapping action of the toggle is entirely freeof the power element. This action is similar to the movement'of the bulb shown in Fig. 6, the mercury bulb-being instantaneously snapped a relatively great distance whereby to positively throw or move the mercury out of making position. The travel of the shoe 9 is very fast and is unhampered by any weight orinertia of the power element. ue to the play between the shoe and plunger, the bulb is snapped or thrown instantaneously, thus being moved much'faster than the shoe 9, due'to the pine and-slot connection between the link 27 and the shoe 9, the pin moving toward the bottom of the slot, as the shoe catches up with v the link. i V

It will thus be obvious that we have provided a very simple, compact and relatively inexpensive control device which is positive q iro taneous snapping action which eliminates a l possibility of arcing due to separated globules of mercury. It will be obvious that the various parts entering into our compact structure are all adjustable, and that in the event of breaking or necessary replacements, they are very easily replaceable. The various adjustments are also possible without removal of any parts or the complete mechanism. It will also be obvious that by reason of thedouble lost motion connection that it will be possible to obtain considerably less movement of the bulb'prior to snapping, as compared to common practice, and considerably more and a quicker movement after snapping, as compared to standard practice.

It will be understood that our novel device may be util zed in connection with controlling the making and breaking of the electrieal circuit in general and is not limited incomprising any manner to the type or design of the power element. V

That we claim is: Y

1. A'control switch for electrical circuits, in combination a pivotally mounted bulb of the mercury spaced terminal type, actuating means, a link pivoted to the mercury bulb structure, a lost motion connection between said link and actuating member, and spring pressed toggle links operativelyconnected to said link at said point of said lost motion connection whereby said mercury bulb will be given a snapping action independently of the actuating means.

2. A control switch for electrical circuits comprising in combination a pivotally mounted bulb of the mercury, spaced terminal type, an actuating member, connecting means between said actuating member and sald pivotally mounted bulb, a pm and slot connection between said connectmg means and said bulb, and spring actuated means for actuating said connecting means.

3. A control switch for electrical circuits comprising in combination a pivotally mounted bulb of the mercury, spaced terminal type, an actuating member, connecting means between said actuating member and said pivotally mounted bulb, a pin and slot connection between said connecting means and said bulb to permit the bulb to be moved for a limited distance independently of the connecting means, and spring actuated means for frictionaily controlling movement of bulb during said independent movement.

4-. A control switch for electrical circuits comprising in combination a pivotally mounted bulb of the mercury tube type, an actuatin member, a link pivotally connected 340 to said mercury bulb structure, connecting means between said actuating member and said link, a lost motion connection between said linkand said connecting member, and toggle means adapted to be moved toward dead center by said connecting means and ,adapted to snap the mercury bulb the distance of said lost motion connection upon bein g moved past dead center.

5. A control switch for electrical circuits comprising in combination a pivotally mounted bulb of the mercury spaced terminal type, an actuating member comprising a plunger, a shoe mounted on said plunger and having a lost motion connection therewith, means connecting said shoe and said mercury bulb, said connection being of the pin and slot type, and spring pressed means actuated by movement of said plunger for imparting a snap action to said bulb, the movement of said bulb being independent of said shoe by reason of said pin-and-slot connection.

'6. A control switch for electrical circuits, comprising in combination a pivotally mounted bulb of the mercury tube type, an

actuating member, operatively positioned to actuate said bulb, spring'pressed means for giving said bulb a snap movement independently of said actuating member, a lost motion connection between said spring pressed means and said bulb and friction means other than said spring pressed: means for. holding said bulb in snapped position.

7. A control switch for electrical circuits, comprising in combination a pivotally mounted bulb of the mercury tube type, an actuating member, connecting means between said pivoted mercury bulb and said actuating member including spring pressed means for giving said bulb a. snap movement independently 01": said actuating means, and friction means other than said spring pressed means for holding said bulb in snapped position but allowing said bulb to be moved by said actuating means.

8. A control switch. for electric circuits, comprising in combination a pivotally mounted bulb of the mercury tube type, actuating means therefor, and having a predetermined lost. motion connection therewith, means for snapping said mercury bulb and having a limited lost motion connection therewith, and means for frictionally holding said bulb in snapped position.

9. A control switch for electrical circuits, comprising in combination a pivotally mounted bulb of the mercury spaced terminal type, a power operated plunger movable toward and from said pivotally mounted mercury bulb, a shoe carried by. the top of said plunger and having a lost motion connection therewith, a pin in the top of said shoe, spring pressed toggle levers operatively contacting with said pin and adjustably mounted in a position substantially at right angles with the movement of said plunger, and an adjustable link connecting said shoe and said pivotally mounted mercury bulb, the

connection between said link and said shoe being by means of a pin-and-slot.

In testimony whereof we aflix our signatures. FRANK R. WEST. THOMAS E. CARPENTER. 

